Forget Guns, 3-D Print Yourself An Invisibility Cloak Instead

The cloak resembles a frisbee with complex holes in it, each of which is carefully positioned so that microwave beams are deflected through them in a way that makes the cloak "transparent" to microwaves. It can thus hide an object (like a highly reflective metal can) from the incoming microwave energy—meaning, of course that it's only "invisible" to this sort of radiation.

But the team is confident that as 3-D printing tech advances quickly over the coming years, the same technique can be extended to work for higher wavelengths, including visible light. Harry Potter: Eat your heart out.